Magnetic separator



R. PLANIQL MAGNETIC sEPARAToR Jan. 15, 1952 2 SHEETS-SHEET l Filed sept.21, 1945 INVENTOR Rene Plafu0 ATTORNEYS Jan. 15, 1952 R, PLANlQL2,582,274

MAGNETIC SEPARATOR Filed sept. 21, 1945 2 SHEETS-SHEET 2 lNvENToR RenPlanz'oZ ATTORNEYS Y Patented Jan. 15, 1952 MAGNETIC SEPARALTORRenLPlanioL.NewfYork, N..Y.,-assignor vtc Pluro, .Inc.,.New'Xork,IN. Y.,.a corporation of New ork ApplicationSeptember 21, 1945,SerialNoam-7,711

'.i23lClaims. '1 The present inventionrelates vtotthe `vart of .magneticseparation,4 that .is .of lseparating mag- .'neticfromenonemagnetic.particles of. negranu- --lar. lorpowdered. ore.` or otherfcomminutedstock.

It-,rsfamong:thefobjects of theinventionV tovlpro- `ride-.1a.method andIcompact apparatus forconk.timiously performingsuchvmethod,:-expeditiously fand-.zeiectively .to segregate .the magneticfrom thetnonamagneticparticles of-icomminutedesuch Las ,1 powdered oreorother` istock,weven lthough .of Sticky or tackycharacterffwithout thelikelihood -of;jamln.r.1gf;or clogging, 1. or the' needforginterfruptingf. the Dperationto .clear-.the mechanism.

In fthe. accompanying drawings :in v-vvliicii Vare shown-one or morelfofvarious possibla embodi- .ments .fof the V,several e features f of `.theinvention, Eig t 1 is a view in 1 longitudinal lcross-jsectionsrshowingithe right half l onlyfof. one embodiment of the equpment fWithpartsv .broken away,

Fig. .1a.fis ra rfragmentary detailed-fviewf show- ...ing .the-airtighthousing,

Fg..2 isfa transverse fcrosssectional.view-taken `:.onwlf e: 2-.2-;of.Fig.;.1.

v Eig..;;.3-f is'a .transverse-cross sectional view. taken on line 3-3of Fig. 1,

vFig. ,4 .isY a. transverse vcrossfsectional:viewtaken l -ongline 4-4 ofFiglyl,

.z-Figgfis-:a fragmentary.sectional'fview indicating the approximate.magnetic .ilux "and '.the ...trajectory vfof .the lmagnetic -and .of ztherznonemag- .gnetic 1; particles :in the .traverse :thereof p throughthe machine A:the length fof the air; gap -`being .-.greatlyyexaggerated :and the :freed wrotor .-being omitted for:clarity-:ofdisclosure, :and

. fFigr vis ja -ragmentaryzsectional views:similar ltingat therouterrimsand spacedlattheir. inner rims. to Henne.. an.. airgap..Gtherebetween.

Thetwoelements .of the .magnet .eldistructure the upper .ofwhichhouses,the co'il ..C, are Mdesir- .ablysecuredtogether .bymoreor lessCouven-45 ftionall'ange piecesA l2. and. i3.about.their respec-"tverims, which are'bolted Atogetheras at4 l4`.to

maintain an interposed gasket g Aunder comilpression.

1 ".The magnethas .annipper .annular .pole ll5v,l

trianglewith a relatively rounded apex. "The an- .l airgap.,are.drawndownward. The magneticflux is distributedsubstantially.asindicatediinthe lfragmentary.view of Eig.5,.todetermine.,a1 .plu .rality of .spaced concentric annular magnetic`iields rising from the .respective .annular t.pole

.l5 -ridgesl l. 6,..l.'l, .(8. .The electromagnet isdesirably4.constructed .to aiorda `flux vthrough the. .gap G oi"..'the..maxirm1m.practicalintensitwi. e.. o`f. about u10,060 Gauss.

.According .to the invention,.thestocktobe .separatedishurled.outwardlby ,centrifngal force radially across 'thear` gap() of themagnet. "To `this. end, a. feed rotor 29.',is provided, which`comr.prisesa horizontal,.plate'. ZILhaVing ra rim' 22 nearVthe..inneranniilar magneticpole ridge .[6 vand whichis atalevel.slightlyabove.the.apex ofsaid ridge. and-welll.belowtheupper polel5. The rotor Y is .desirabiy .mounte'don the upper v,end of anvupright'hollow `.driving vshaft 23 extending .axially vthrough the ..magnetstructure, lodged "hall 0 lbearings 24 and '25, and A.driven @from a..suitable u `source .of power (not shown), .as .'for instance,througha'pulley .26 aboutthe' lowerlend.. ofithe said shaftv23.

A upole. Shield `.lil v.guards ',Ithe lower `pole ,piece `fromdirectengagement by the magnetic particles. "The pole vshield. isaring'desirablybt not vnecessarily `of .non-magneticmateriaLv-preferably.. metal .aliixed .at its hub .2.8 .to .the end `olahollowshaft' 29m/nich desirably encloseslthe shaft 40 .23 .previously...described turns'in ballbearings 30.' 3 I, .andis driven byasuitablelsource, of .power (not shown), as.`for instancev'throughpulley'ld on .its lower end. Ifhe .pole shield .extends4'ololidnely upwar'difrom itsliub past'the ,beveled edge] I..offfe edrotorl20 .and has Ja .thin .horizontal annular web32eXten'ding voveraridlbridg- '.ingbetWeen fthe annlarpole ridgeS'l6,. |1,.1l8 of the'.lowerpole said shieldihaving a."s`kirt.`33 ex- .tending over .ftheouteriace of the -,outergpole .ridgell8. The ridgebridging Web.32 ofthepole shield" 21'. is preferably.substantially. inthe plane .of theyfeed rotorplate'Z'l.

To .sggrcgate'the magneticparticles d'eiiected 4bythe'action vof the,pole .ridgesfi 1.1,. I8 Irom the nonemagneticparticles.hurledoutwardibythe structure.

cone.

feed rotor without such magnetic deflection, an interceptor ring 35 isprovided. That interceptor ring is a conical wall about the outer poleridge I3, presenting an upper sharp edge 35' substantially at the levelof the feed rotor plate 2l.

The interceptor cone is preferably secured at its lower edge upon theupper edge of a cylindrical median Wall 36 constituting a unitary partof the magnetic frame structure below the pole. Radi-al walls 31 connectthe median wall to the inner and to the outer walls of the magnetstructure and are integral therewith. The magnet thus presents acellulal` structure at its lower part, with sector-shaped cellsincluding an inner tier 38 within the wall 35 and an outer tier 33 "fromadhering tothe wall of the equipment. To this end, skirt 33 of the poleshield rotor is pro- `vided with a series of unitary triangular vanesl40, the outer oblique edges 4I of which substantially run across theinside of the interceptor 35. Likewise the' feed rotor 25 is de'sirablyprovided with a' unitary dat flange 42 extending outward radially acrossthe width of the lower pole ridges I6, I1 and I8 and across theinterceptor cone 35 substantially to the outer wall of the magnet poleThe flange 42 mounts at the lower face thereof ;a series of vanes 43which have an upright outer wall moving along the bore of the magnetstr-ucture and an inclined inner wall 44 moving along the outer face ofthe interceptor Desirably both the said vanes 4e .and 43 are in planesinclined to the vertical so that in the rotation of the respective partsthe material will not.' only be loosened but urged downward 'into andthrough the respective cells 38 and 39.

The feed rotor is desirably a hollow conical structure comprising thecircular plate 2l and a fiat hollow cone 45 coaxial therewith andconnected thereto by radial fins 46. The hollow'cone denes a narrownozzle at the periphery 22 of plate 2l, and the flange 42 extendsoutward from the cone above said nozzle.

Collector means is provided for the segregated vmagnetic andnon-magnetic particles and con.

venient means for withdrawing the same from the machine, To this end anannular drum 41 may be disposed directly under the` magnet structure andaixed thereto as at 48.

This annular drum has a door 49, an inner wall 55, .and an outer wall I,the latter desirably flush with the magnet structure. In the drum thereis .desirably mounted a rotor comprising an upstanding annular medianwall 52, said wall having an upstanding peripheral n 53 preferablytelescoped into the correspondingly bifurcated lower edge of the magnetdividing wall 36. The rotor wall 52 is desirably provided with aplurality of blades 55 extending to the inner periphery of the drum vandblades 56 to the outer periphery thereof.

Said inner blades are connected by bridge piece 51 to a shaft 58 mountedon ball bearings 59, 60 coaxial with shafts 23 and 29, and driven as bya pulley 6i. The floor of the drum has an outlet 62 at one side of therotor wa11` 52 for discharge of the magnetic particles therethrough anda similar outlet 63 at the other side of the annular wall 52 fordischarge of the non-magnetic particles. The blades 55 and 56 arepreferably inclined to the vertical, positively to push the collectedm-aterial through the respective ports 62 and 63.

To avoid interfering with the eicacy of separation at the pole piece bythe effect of the turbulence of air at that region, the machine isdesirably kept under a Vacuum applied by a suitable pump (not shown) asthrough a port 64 in the magnet wall. Such vacuum operation is advisablewhere the grains of powder to be separated are smaller than 1GO microns.

Although any suitable outer air tight housing could be used to containthe unit in order that a vacuum may be maintained, in the embodimentherein shown the housing illustratively comprises Ia casing 12positioned over the feed 12 and a casing 62' enclosing the ports 62 and63.

Since the stock is frequently relatively adhesive in character, theintroduction of an air blast for disintegrating such stock would notordinarily be practical where, as preferred, it is desired to operatethe machine under vacuum. Therefore, the p-resent invention affords ameans for effecting such separation without the introduction of air orgas. To this end, desirably a centrifugal disintegrator plate 65 isprovided. This plate is of relatively small diameter and is co-planarwith the feed rotor plate 2|, it being desirably countersunk within acentral opening 66 in the plate 2l. The disintegrator plate is desirablymounted on the upper end of an inner shaft 61 encircled by shaft 23,said inner shaft rotating in ball bearings 63 and 69 and being driven bysuitable means, Ias by a pulley 10. The disintegrator plate 65 may, ifdesired, have narrow ribs 1I to facilitate operation. The hopper 12 fromwhich the stock to be treated is introduced, feeds through pipe 13directly upon the disintegrator plate 65 which is driven at relativelyhigh speed, effectively to disintegrate the lumped masses of particles.

For clarity, the method of the present invention and the mode ofoperation of the illustrative equipment for carrying such method intoexecution will now be described.

The stock drops by gravity upon the disintegrator plate 6 which isrotated at speed such as to cause any small lumps of iron and clay forinstance, to become disintegrated as they are hurled outward toward thefeed rotor 26. By the feed rotor, the stock thus previouslydisintegrated is hurled outward centrifugallyat high speed through theperipheral nozzle at 22 in an annular stream of small thickness acrossthe annular air gap G. Iny this movement, as will be apparent, themagnetic flux to the innermost of the annular pole ridges I6 selectivelydeflects the magnetic particles downward somewhat, without in any wisehowever affecting the movement of the non-magnetic particles. As thestream is hurled past the second magnetic pole ridge I1, the deectedmagnetic particles are further deflected downward, and thus theoperation proceeds as the stream of particles iiows past the successivemagnetic ridges (which would be of suitable number) until, by the timethe final outer magnetic pole ridge I8 is passed, the deflection will besufficient for the knife edge 35 of the interceptor` cone 35 tointercept the magnetic particles and allow the remaining particles toproceed therebeyond.

v7'1I/'he non-magnetic polelshield rotorv 2 'l' prevents vfthe')magnetic particlesi-fromf-adhering lto-ithe. pole ridges lv6, il'l,i138. It V`is f-driven at 'rsuch speed ft-hat it.' imparts -suiiicsient1 centrifugal :force ".to eany @articles `-in -fcontact l therewith y'tohurl the "same "outward 'along skirt 33 -for release at f the lower partof such skirt, where there is substan- "tially'fnozfmagneticeld.

Theirnachineoperatesllsufliciently vwith ail-righ foutput, `sincethe1-succession of annular :magnet 10 polef-'ridgesrmakes possible a-sucient deflection vStiff-the'frna'g-neticparticles 'in their traverseacross "the radius-of the-fairvgap,'feven1.though the feed frotorf isirevolve'df `atthelltremendous speed neces- `-lsary ifor ra "largeoutput with :consequent .high centrifugal lforce.

f Ashows the yapproximate trajectories. of kthe rnon'magne'tic particles(shownin .dot .and :'iflashllinesl and; off thelmagnetic particles.(shown lfini 'dottedl lines) ,lthe length 'of the magnetic gap 1*betweenthe "poles Ibeing/greatly exaggerated.

"iThus ``the magnetic particles Areleased 'from vnear-the lower edgeofskirt33 will drop into fthe innerftiervof cells 386m the magnetstructurevwhile the non=magnetic .particles that had not been "deected .downwardwill drop into the outer tierof cells39, the vanes 40 onthe skirt `ofEthepoleishield .2lfand .the vanes '43 Von rthe .tllange "42 of the ifeed :rotor :assisting the downl'wardifmovement: of'ithe :segregatedparticles Vand precluding adhesion thereof to `the respective wallflstructures. The separated particles pass fdownwardintothe.drum 4l andthe annular .'oollectorstherein latv opposite sides of there-tor:.ringi52. In theislowpropulsion of the collector =:rotorf.l52 from.thelpulley 6|, Vthe collected `imafterialhisi'sweptoutofthe machineinto suitable receptacles (notfshownLthe magnetic particles throughSport 62 and the non-magneticthrough f-fpo'rtfSB.

:It #will of course .be understood that equipnnentwithas manyorasifewrof the concentric `magnetpole'ridges. I6, I'l, I8, as desired,may be employed. In.:Fig. .6 Ais `shown illustratively a ilfragmentfof:equipment like that .of Fig. l, ex- .lcept :that y:the flower :pole.piece lhas but 'fa 'single annular ridge S lr6. v.'I'he'imachine wouldhave a lcori'espondingly lower-output, .since the centrif-.=..'uga1.:force..applied to .the .'stock' must. not be so high @that.the .single pole ridge would Lfail Ito telectfsufdcient deiiection for`reliable :segrega- Vtionzlof Jthe: magnetic .particlessAsipreviously'indicated, the vacuum .operation isapreferredVsincezthisavoids the entrainment -ofxnona-magnetic .with magneticparticles due toieddycurrents oflair` neartheair gap under the sspeed of .centrifugalpropulsion. 'Where .such '.-vacuumsisxapiilied,` it will vbe understoodthat each of the bearingslis equipped `with a. suitable .oil `,seal vofmore orless lconventional construc-` `cannular:aire gap 1G is say 15centimeters and the widthlofthegap might .be 1 centimeter, the feed-rotorllwouldaloepoperated` at azspeed of 25.00 `or fmoreRJP. M'.; .thepole .shield rotor 21 might be .operatedwataspeed :of 6000 R..P. M. .ormore, andfthezdisintegrator rotor plate 65`at .a speed of .30,00R. P.fM.or. more.

.fhemachineiandimethodare not limited to :the separationrof-magnetic,from other solid par- ..6 faration 1. of .magnetic fparticles r" from.arsstreami .of `igas entraining'ithef same las;` for instance;immediately following fthe .reduction :of `-iron ore. f In this case'vitfwill .tbe apparentithat thexna'gnetic .particles Vwill -be separatedexactly sassabovedefscribed vand 'I the :great :bulkpf'the gas .will.pass ioutward .irom beyond the interceptor ..1cone1z35. izIf 11 thegas. `is .propelledrunder isuitab'leipressure, -the feed rotorr20 couldrbe left .stationary .inlsuch :operationgas will-.be Vimmediatelyapparent.-

,'Asfmany-changes .could .be .made finlthela-bove Dmethod. :andconstruction, and .manyfapparently fwidelyy different 'embodiments `:ofi'this :invention :conldrbezmadewithout departing fromtheiscope :oftheclaims, it is intended thatallamatterfconltained. inztheabovedescription orfshown'lin the :accompanying drawings, .L shall beinterpretedi'as .illustrative:andrnotv inza limitingfsense.

Having thus described myinventiongfwhatll clairn'Y as 1 new and :desirento .secure by Letters -Patent 'of the United States` is i l.Af'fma'gnetic separator, vcomprisingfan:elec- .tromagnethavinganannular. air :gape'with allow- -er pole ofihigher luxdensityfandan upperV pole-,of lowerrflux. density, va feed rotor. encompassed 'lbysaid poles andat levelslightly higher than that of .the lower pole,non-magneticrotarvshield plate .over saidv lower pole, .and 2. aninterceptor ringv 'encompassingisaidlower' pole land .havingian upperedgezfsubstantially at theleveleof :said votary;shield plate, .andAcollectors below -saidfin- '.terceptorl ring andi 'at' `opposite-sidesthereof; respectively, for Athe magnetic and the nonernagneticcomponents.

2. 'A magnetic separator, coniprisingan electromagnet having facylindrical outer fwall an inner v*wall with an .upper relativelyiiat'annular pole and la ylower relatively .sharp 'annularpole -With .anannular :air gap therebetween, a feed rotor encompassedbysaid-airfgap'and at "level lslightly higher than thatof"-the'flower1pole,=an

interceptor ring Vhaving anfannularupper-edge substantially -at .thelevel of vsaid feed rotoreand encompassing the lower pole piece, anannular f -Wall..mounting said interceptor ringior segregation i of the1 non-magnetic particles `yat 'one1side 'thereof -and the magnetic atthe other, -vanesin- `terposed between the interceptor ring andtheinner-and outer walls ofthe magnet structure,"and means 'frfrotatingsaid vvaries tol forcer the Alsepa- .rated'f' particles fdownwardforcollection .thereof.

V3..A./.rn'agnetic separator, comprising van electromagnet structure,vhaving 'a cylindrical outer wall and a generally .cylindricalinnerWall' hav-ing a relatively flat upper annular 'pole piece/and arelatively sharp lower annularpolepiece deter'- lthelower p'ole, anupstanding cylindrical dividing wall within the electromagnet betweentheouter yand innerwallsof'the latter, and an interceptor conesupporting on top` of said dividinglwall-ianfc having an upperseparatoredge nearsaid shield 'cap rotor and 'substantially' at the level4ofthe-'feed rotor, inclined Ivanes interposed'between the in terceptorcone and the outer wall of the electromagnet, inclined vanes interposedi between the interceptor 'coneand the shield-cap rotor, `and meansforrevolving said'vanes about the axis' 'of the separator.

4. The combination recited in claim 3, ina-'nich `thevanes at theouterside ofthe interceptor cone fzticles'ibut'may bensed `tonadvantagefforthe. sepr"l are 'rigidfwith thel feedf rotor.

5. The combination recited in claim 3, in which the vanes at the innerside of the interceptor cone are rigid with the shield cap rotor.

6. A magnetic separator, comprising an electromagnet structure having acylindrical outer wall and a generally cylindrical inner wall, thelatter having a relatively flat upper annular pole piece and arelatively sharp lower annular pole piece determining an annular air gaptherebetween, afeed rotor encompassed by said air gap presenting anannular nozzle adjacent said air gap and at level slightly higher thanthe lower pole piece, said rotor including an annular flange extendingoutward from the upper edge of said nozzle to nearly the inner face ofthe outer Wall of the magnet structure, an interceptor ring about theair gap at substantially the level of the feed rotor, a series ofinclined vanes rigid with the lower face of said flange and interposedbetween the interceptor ring and the outer wall of the casing, anon-magnetic shield cap rotor coaxial with said feed rotor and extendingwith small clearance along the lower pole piece and a series of inclinedvanes affixed to the outer portion of said shield cap and rotatingtherewith alongthe inner wall of the interceptor ring.

7. A magnetic separator, comprising a generally cylindrical hollowelectromagnet shell, having a continuous cylindrical outer wall and aninterrupted interior wall presenting an upper pole piece, a lower polepiece of greater flux density and an annular air gap therebetween, meansfor introducing the stock axially of the separator, a feed rotor atlevel slightly higher than that of the lower pole piece, an interceptorring having an upper edge at substantially the level of said rotor andintercepting magnetic particles subjected to both magnetic andcentrifugal action, While passing non-magnetic particles subjected onlyto centrifugal action.

8. A magnetic separator of the type claimed in claim 7, encased undervacuum, and means for breaking the adhesion between particlespreliminary to the separator action, said means comprising a small rotorplate encompassed by the feed rotor and at substantially the levelthereof.

9. A magnetic separator, comprising an electromagnet casing structurehaving a cylindrical outer wall, annular pole pieces spaced inwardtherefrom with an annular air gap therebetween, the upper of said polepieces being relatively flat and the lower relatively sharp, a pluralityof upright coaxial drive shafts encompassed by the electromagnet, one ofsaid drive shafts having a feed rotor affixed thereon, said rotorpresenting a horizontal plate extending at its periphery near andslightly above the lower pole piece and encompassed thereby, one of saiddrive shafts having a non-magnetic shield cap rotor thereon extending inpart under said feed rotor, and over and along the effective outer areaof the lower pole piece.

10. A magnetic separator, comprising an electromagnet casing structurehaving a cylindrical outer wall, annular pole pieces spaced inwardtherefrom with an air gap therebetween, the upper of said pole piecesbeing relatively flat and the lower relatively sharp, a plurality ofupright coaxial drive shafts encompassed by the electromagnet casing,one of said drive shafts having a feed rotor affixed thereon, said rotorpresenting a horizontal plate extending at its periphery near andslightly above the lower pole piece and encompassed thereby, a second ofsaid drive shafts having a non-magnetic shield cap rotor thereonextending in part under saidfeed rotor and capping the lower pole pieceand extending along its effective outer area, and a third of said driveshafts having a rotor disk substantially at the level of and encompassedby the feed rotor, and a hopper introducing the stock to drop upon saiddisk.

l1. A magnetic separator, comprising an electromagnet casing structure,having a cylindrical outer wall, annular pole pieces spaced inwardtherefrom with an air gap therebetween, the upper of said pole piecesbeing relatively fiat and the lower relatively sharp, a plurality ofupright coaxial drive shafts encompassed by the electromagnet, one ofsaid drive shafts having a feed rotor affixed thereon, said rotorpresenting a horizontal plate extending at its periphery near andslightly above the lower pole piece and encompassed thereby, a second ofsaid drive shafts having a non-magnetic shield cap rotor thereonextending in part under said feed rotor, capping the lower pole pieceand extending along its effective outer area, generally annularseparator cells between the inner and outer walls of the electromagnetand below the pole pieces thereof, said cells having a. cylindricalseparator `wall concentric and between the inner and outer walls of theelectromagnet, and an interceptor ring rising from the upper end of saidseparator Wall and having an upper edge at substantially the level ofthe shield cap.

l2. A magnetic separator, comprising an electromagnet casing structure,having a cylindrical outer wall, annular pole pieces spaced inwardtherefrom with an air gap therebetween, the upper of said pole piecesbeing relatively fiat and the lower relatively sharp, a plurality ofupright coaxial drive shafts encompassed by the electromagnet, one ofsaid drive shafts having a feed rotor affixed thereon, a second of saiddrive shafts having a non-magnetic shield cap rotor thereon extending inpart under said feed rotor, capping the lower pole piece and extendingalong its effective outer area, generally annular separator cellsbetween the inner and outer walls of the electromagnet and below thepole pieces thereof, said cells having a cylindrical separator wallconcentric rwith and between the inner and outer walls of theelectromagnet, an interceptor ring rising from the upper end of saidseparator Wall, and having an upper edge at substantially the level ofthe shield cap, said feed rotor comprising a flat hollow conicalstructure presenting a thin peripheral nozzle, near and slightly abovethe lower pole piece, said conical structure having a fiat fiange abovethe nozzle extending over the lower pole piece and its cap shield, overthe interceptor ring and substantially to the outer wall of theelectrcmagnet casing.

13. A magnetic separator, comprising an electromagnet casing structurehaving a cylindrical outer wall, annular pole piecesv spaced inwardtherefrom with an air gap therebetween, the upper of said annular polepieces being relatively at and the lower relatively sharp, a pluralityof upright coaxial drive shafts encompassed by the electromagnet, one ofsaid drive shafts having a feed rotor affixed thereon, a second of saiddrive shafts having a non-magnetic shield cap rotor thereon extending inpart under said feed rotor, capping the lower pole piece and having askirt over its outer face, separator cells in the electromagnet andbelow the pole pieces thereof. a cylindrical dividing wall. through saidcells concentric with and between the inner and outer having :an upper`edge -at substantially the level of -theyshield cap, -said ,feed `rotorcompri-sing a ffiat, hollow conical structure determining a thinperipheral nozzle -encmpassed by the air gap, Asaid conica-l structurehaving a 1l-at outstanding iiange above the nozfzle extending 'over thelower pole piece, its -cap shield and the interceptor ring andf'substantially .to kthe -outer wall of Athe electromagnet casing, andinclined vanes respec- .Atively on ythe skirt of the shieldcap rotorand'on the underwall of the outstanding flange, said vanes respectivelyclearing the inner wall `of the interceptor ring and the inner surfaceof Athe 4outer wall `of theelectromagn'et. y

.14. A magnetic separator, comprising an elec- `.trornagnet structure,having a cylindrical outer wall, va generally cylindrical inner wallpresent- ,ng :an annular relativey dat upper pole piece and an annular'relatively sharp lower pole piece, bothspaced from the topand bottom ofthe electromagnet structure, :the lower fpart 'of the electromagnetstructure below the .lower pole piece presenting radiating ribs ,and amedia-n annular .wall,-dening segment yshaped cells, a ycollector drumdirectly under the electromagnet structure, an annular separator wall insaid drum -diirectly below ,the median annular wall, dening :annular,collector receptacles, and discharge ports .from opposite :sides of theannular sepa- .sta'ntally the level thereof,.for .directing .themagnetic particles toward the .inlet side thereof through the innermagnet cells to the corresponding innercollector receptacle and forhurling ythe non-magnetic particles through the outer :cells to thecorresponding outercollector receptacle.

15. vThe combination recited in claim 14, in which the-annular separatorwall is rotatably mounted, in which drive means constantly revolves thesamefand in which vanes unitary with and -at 'opposite sides of ,said:separator wall are rotated therewith and break adhesion lof theparticles with the respective walls, the discharge ports being in thebottom of the drum.

16. In a magnetic separator, an electromagnet structure, consisting oftwo annular pieces each generally U-shaped in radial cross-section andsecured in abutting relation at their outer rims, the inner annularedges of the structure being spaced and defining poles, the upper ofwhich is relatively flat and the lower relatively sharp, the lower ofsaid electromagnet pieces having longitudinal cells therethrough belowthe pole piece, said cells comprising an inner tier and an outer tier, acylindrical separator wall of the magnetic structure between said tiers,and an interceptor wall rising from said separator wall and presentingan upper edge encompassing and slightly above the lower pole.

17. A magnetic separator comprising an electromagnet structureconsisting of two annular pieces, each generally U-shaped in radialcrosssection and secured in abutting relation at their outer rims, theinner annular edges of the structure being spaced and dening polepieces, the upper of which is relatively flat and the lower relativelysharp, the lower of said electromagnet pieces having longitudinal cellstherethrough below the pole piece, said cells comprising an 1'0 innertier and an outer tier, a cylindrical dividing wall of the magneticstructure between said tiers, a conical interceptor well rising fromsaid dividing wall and presenting an upper ledge encompassing andslightly above the lower pole piece, ymeans `for introducing the stockaxially downward through the annular electromagnet structure, aplurality of rotors for treating Asaid stock at substantially the levelof the air gap, up-right shafts coaxially through the structures fordriving said rotors, said rotors including a feed rotor with itsperiphery near the air gap and. slightly above .the lower pole, andavshield cap rotor over the lower pole piece.

18. A magnetic separator comprising an electromagnet structure, said.structure .consisting `of two annular elements each generally U-shapedin .radial cross section and secured in abutting relation at their outerrims, the inner `annular edges of the .respective elements defining`spaced pole pieces, :the upper of which is relatively lilat and thelower relatively sharp, the lower of said elements havinCr longitudinalcells therethrough below the pole piece thereof, said cells comprisingan inner tier andan outer tier, a cylindrical dividing `wall of themagnetic structure between ,said tiers, an interceptor cone rising fromsaid wall and presenting an upper edge Aencompassing and slightly abovethe lower pole piece, means introducing the rstock axially downwardthrough the annular lelectromagnet structure, ,a

plurality of rotors for treating `said stock subsstantially `at thelevel of the air gap, upright shafts extending coaxially through theannular magnetic structure ,for driving ysaid rotors, said rotorsincluding a feed rotor with its periphery near the air gap and-rslightly above the .lower pole, a shielding pole cap rotor over thelower pole piece, a collector drum vcoaxial with and ,im-

kmediately below the electromagnet structure, said vdrum having anannular rotor therein, comprising a median wall extending the height ofthe drum and telescoped with respect to the lower edge of the dividingwall of the magnet, said median wall having vanes rigid therewithextending'to the opposite faces ofthe drum, drivemeans coaxial with therotor drives for slowly driving said annular rotor within its drum, said`drum having ports in its iloor at .opposite sides of the median wall ofthe rotor therein for discharge of the segregated magnetic andnon-magnetic material therefrom.

19. A magnetic separator, comprising an electromagnet structureconsisting of two annular elements, each generally U-shaped in radialcross-section and secured in abutting relation at their outer rims, theinner annular edges of the respective annular elements defining spacedpole pieces, the upper of which is relatively flat and the lowerrelatively sharp, and defining an air gap therebetween, the lower ofsaid elements having longitudinal cells therethrough below the polepieces, said cells comprising an inner tier and an cuter tier, acylindrical dividing wall of the magnetic structure separating saidtiers, an interceptor cone rising from said dividing wall and presentingan upper edge encompassing and slightly above the lower pole piece,means for introducing the stock axially downward through the annularelectromagnet structure, a plurality of rotors for treating said stocksubstantially at the level of the air gap, concentric upright shaftsaxially through the magnet for driving the several rotors, said rotorsincluding a feed rotor with e its periphery near the air gap andslightly above the lower pole, a shielding pole cap rotor over the lowerpole piece, a nat rotor plate substantially in the plane of andencompassed by the inner periphery of the feed rotor, an'annuiarcollector drum coaxial with and immediately below the magnet, said drumhaving an annular rotor therein with a median wall extending the heightof the drum and telescoped with respect to the lower edge of thedividing wall of the magnet, said annular rotor having vanes rigidtherewith extending to the opposite faces of the drum, drive meanscoaxial of the rotor drives for slowly driving said annular rotor withinits drum, said drum having outlet ports in its floor at opposite sidesof the median wall for discharge of the segregated magnetic andnon-magnetic material therefrom.

20. A magnetic separator, comprising an elecftromagnet structure havingcoacting annular elements each U-shaped in radial cross-section,

abutting at their outer rims and presenting spaced annular pole piecesat their inner periphery including a relatively at upper pole piece anda relatively sharp lower pole piece, the lower magnet structure belowthe pole piece thereof being longitudinally cellular and including twotiers of cells having radiating walls and having a cylindrical dividingwall, an interceptor cone rising from said dividing wall and having anupper edge encompassing and slightly above the lower pole piece, meansfor introducing the stock axially and longitudinally through the magnetstructure, and a series of rotors for handling the material, said rotorscomprising a feed rotor and la shielding cap rotor, concentric shaftsdriving the respective rotors, the feed rotor hurling the stockperipherally outward and the shielding cap rotor precluding adhesion ofthe magnetic material to the pole, and a drum coaxially of the structuredisposed directly under the magnet, having a rotor therein, presentingan annular wall registering with the dividing walls, vanes rigid withsaid annular wall and adjacent the reand non-magnetic material.

21. A magnetic separator comprising a pair of annular magnet elementseach U-shaped in radial cross-section determining a cylindrical outerwall and spaced annular pole pieces at its inner wall, defining an airgap therebetween, an interceptor ring about said air gap, the upper ofsaid pole pieces being relatively flat and the lower of said pole piecescomprising a plurality of spaced concentric relatively sharp annularridges, a feed rotor encompassed by said lower pole piece and presentinga rim adjacent the inner of said annular pole ridges and slightly abovethe level thereof, and a non-magnetic pole shield rotor coaxial withsaid feed rotor and extending across the width of said lower annularpole piece and the several annular ridges thereof.

22. The combination recited in claim 21, in which the feed rotorcomprises a hollow wide based cone, presenting a thin annular nozzleabout the base thereof and in which said cone has a unitary flat flangeextending outward substantially to the wall of the electromagnetstructure, and in which the base of the electromagnet -has a cellularstructure including a cylindrical REFERENCES CITED The followingreferences are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 455,984 Fiske July 14, 1891456,622 Lain July 28, 1891 1,072,277 Ullrich Sept. 2, 1913 2,227,280Smith Dec. 31, 1940 FOREIGN PATENTS Number Country Date 194,711 GermanyJan. 27, 1908 267,200 Germany Nov. 13, 1913

